Question

Arrange the following coordination compounds in the increasing order of magnetic moments. (Atomic numbers: $Mn = 25; Fe = 26$)
(1) $[FeF_6]^{3–}$
(2) $[Fe(CN)_6]^{3–}$
(3) $[MnCl_6]^{3–}$ (high spin)
(4) $[Mn(CN)_6]^{3–}$

• A. 1 < 2 < 4 < 3
• B. 2 < 4 < 3 < 1
• C. 1 < 3 < 4 < 2
• D. 2 < 4 < 1 < 3

Answer 1

Answer: (B)

2 < 4 < 3 < 1

Answer 2

$Coordination\; Compound$	$Number \;of \;unpaired \;e^– (n)$	$Magnetic \;moment \;(μ) (B.M)$
$A\;[FeF_6]^{3–} – d^5$	5	5.91
$B\; [Fe(CN)_6]^{3–} – d^5$	1	1.73
$C \;[MnCl_6]^{3–} – d^4$	4	4.89
$D\; [Mn(CN)_6]^{3–} – d^4$	2	2.82

Hence, the correct order of magnetic moment is $2 < 4 < 3 < 1$